Electrochemical Biochip Assays Based on Anti-idiotypic Antibodies for Rapid and Automated On-Site Detection of Low Molecular Weight Toxins

Abstract

Phycotoxins and mycotoxins, such as paralytic shellfish poisoning toxins, type A trichothecenes, and aflatoxins are among the most toxic low molecular weight toxins associated with human poisoning incidents through the consumption of naturally contaminated food. Therefore, there is an utmost need for rapid and sensitive on-site detection systems. Herein, an electrochemical biochip for fast detection of saxitoxin, T-2 toxin as well as aflatoxin M1 and their corresponding congeners, respectively, using a portable and fully automated detection platform (pBDi, portable BioDetector integrated) was developed. Toxin analysis is facilitated upon the biochip via an indirect competitive immunoassay using toxin-specific antibodies combined with anti-idiotypic antibodies. The developed biochips enable detection in the low ng/mL-range within 17 min. Moreover, the assays cover a wide linear working range of 2–3 orders of magnitude above the limit of detection with an inter-chip coefficient of variation lower than 15%. The broad specificity of the employed antibodies which react with a large number of congeners within the respective toxin group allows efficient screening of contaminated samples for the presence of these low molecular weight toxins. With respect to the analysis of human urine samples, we focused here on the detection of saxitoxin, HT-2 toxin, and aflatoxin M1, all known as biomarkers of acute toxin exposure. Overall, it was proved that the developed biochip assays can be used to rapidly and reliably identify severe intoxications caused by these low molecular weight toxins.

Direct-Write Bioprinting Approach to Construct Multilayer Cellular Tissues

“…The technique is based on a programmable noncontact piezoelectric inkjet bioprinter with a resolution of 5 µm and a minimum deposition volume of 300 pL. Such a system has been frequently applied in researches, especially for ultra-low volume liquid handling of nanoparticles (Scherbahn et al, 2016), drugs (Tronser et al, 2018), and biomolecules, such as proteins (Kilb et al, 2019) and antibodies (Marquette et al, 2012;Schulz et al, 2019).…”

An Electrochemical Fiveplex Biochip Assay Based on Anti-Idiotypic Antibodies for Fast On-Site Detection of Bioterrorism Relevant Low Molecular Weight Toxins

“…The ideal capture mAb (mAb1 or mAb2) as well as the concentration used for immobilization were selected during competitive tests prior to the multiplex set-up (data not shown). The utilized mAb pairs for STX, T-2 and AFB1 were the same as those characterized previously in singleplex electrochemical biochip assays [35]. Selection of the respective Ab type as capture is the crucial step regarding assay sensitivity, because the competitive reaction is dependent on the amount and functionality of the mAb on the electrode surface [35] (see also Figure S1).…”

“…The utilized mAb pairs for STX, T-2 and AFB1 were the same as those characterized previously in singleplex electrochemical biochip assays [35]. Selection of the respective Ab type as capture is the crucial step regarding assay sensitivity, because the competitive reaction is dependent on the amount and functionality of the mAb on the electrode surface [35] (see also Figure S1). Suitable capture mAbs (STX/mAb2, MC-LR/mAb2, T-2/mAb1, RoA/mAb2, AFB1/mAb1) were immobilized onto the biochip in duplicates on interdigitated array (IDA) gold electrodes consisting of two interlocking sets of anodic and cathodic fingers ( Figure 1).…”

“…Particularly, anti-idiotypic antibodies of β-type (Ab2) raised against the paratope of the toxin specific antibody (Ab1) mimic the epitope of the target toxin and compete with the analyte for specific binding to the corresponding Ab1 [31], and can be used either as capture antigen [32], as competing detection reagent [33] or as surrogate toxin [34] in immunoassays. Previously, we reported the utilization of monoclonal Ab2 (mAb2) to develop microarrays for singleplex detection of STX, T-2/HT-2 or aflatoxin M1 (AFM1) and proved their applicability for analyzing human urine samples [35].…”

A Carbamoylase-Based Bioassay for the Detection of Paralytic Shellfish Poisoning Toxins

“…Several biosensors and immunoassays based on monoclonal and polyclonal antibodies have been proposed for PSTs' detection [10,11]. The most commonly used detection platforms include surface plasmon resonance (SPR) biosensors [12][13][14][15][16], enzyme labeled immunosorbent assay (ELISA) [13,17,18], flow cytometric assay [19] and optical [20,21] and electrochemical [22] biosensors.…”